C ASP, net core framework value transfer method and session use

  controller

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Database_First625.Controllers
{
    public class FirstController : Controller
    {
        public IActionResult Index()
        {
            base.TempData["u1"] = "temo data u1";
            base.ViewBag.u2 = "temo data u2";
            base.ViewData["u3"]= "temo data u3";
            string data = "this data";
            // session Pass value , Not successfully output  
            base.HttpContext.Session.SetString("u4","this is session");


            return View("Index",data);
        }
    }
}

  View

 

@using Microsoft.AspNetCore.Http;
@{
    ViewData["Title"] = "Index";
}

<h1>Index&l